sbt 0.13 compatibility (avoid deprecated operators)

[SethTisue]

dbuild inserts stuff into builds that uses the <<= operator, which is deprecated in sbt 0.13

this causes noise in build logs:

[mima:error] /home/jenkins/workspace/scala-2.11.x-jdk8-integrate-community-build/target-0.9.5/extraction/fd166a3742340e0d03d17622d468651861ad2ebf/projects/fe5fc9dbf0fed7d1455995b72f37ed6ce3592ebc/project/ÿÿÿÿÿÿÿÿÿÿ~~~~dbuild~defs.sbt:1: warning: <<= operator is deprecated. Use key := { x.value } or key ~= (old => { newValue }).

worse, if somebody has -Xfatal-warnings enabled for their build definition itself, it fails the build

fyi @dwijnand

[dwijnand]

@SethTisue From looking at the sources of where dbuild writes that defs.sbt file I think these are coming from the extra settings you inject:

• https://github.com/scala/community-builds/blob/2.12.x/community.dbuild#L47
• https://github.com/scala/community-builds/blob/2.11.x-jdk8/common.conf#L139
• https://github.com/scala/community-builds/blob/2.11.x/common.conf#L133
• https://github.com/scala/community-builds/blob/2.12.0/community.dbuild#L47

[SethTisue]

doh. ok, I'll fix

[SethTisue]

well, actually:

[acyclic:error] onLoad in Global <<= (onLoad in Global) { previousOnLoad => previousOnLoad andThen { state => { com.typesafe.dbuild.plugin.DependencyAnalysis.printCmd(state,previousOnLoad) } }}
[acyclic:error]                  ^

I think this one is coming from dbuild.